Straight beam adjustable jaw clamp



Jan. 3, 1956 J- ELLIOTT STRAIGHT BEAM ADJUSTABLE JAW CLAMP Filed March7, 1952 llwifbtol ZELL (Jot-b STRAIGHT BEAM ADJUSTABLE JAW' CLAMP JohnElliott, London, England, assignor to Acrow (Engineers) Limited, London,England Application March 7, 1952, Serial No. 275,410

3 Claims. (Cl. 144-291) This invention relates to clamps and'moreparticularly clamps Which are used for holding together the formwork ofeasing used for casting concrete beams in situ.

The invention consists of an open beam structure, a pair of clampingarms sliding therein and mounted respectively on leftand right-handedthreaded portions of a screw member, whereby the arms can be adjustedfrom one side only by turning a key or handle which rotates the screw.This adjustment can easily be made and operates the arms quickly,precisely and to the exact measurement.

The invention will be further described with reference to an embodimentshown in the accompanying drawing.

In the embodiment, a beam structure comprises two flanged side-beams Ijoined at the bottom by a closing plate 2, the beam structure being leftopen at the top, except for a closing plate 3 in the middle and anglebrackets 4 at the end as detailed later.

The front side-beam 1 in the drawing is shown partly cut away to showthe structure beneath.

Within the beam structure there are arranged to slide two L-shapedstructures, the vertical members 5 of which form the clamping arms andthe horizontal members 6 of which slide along the bottom of the beam.Two angle brackets 7 are provided, one on each side of the uprightmembers to slide on the top faces of the side beams. The verticalmembers of the L-shaped structures are braced to the horizontal membersby means of an inclined member 8 and this too has a bracket 9 on eachside to slide on the top faces of the side beams.

At each end of the beam there is a flanged end member 10 the front oneof which in the drawing supports one end of a screw member 11 whichprojects through the flanged end member 10 with a square end over whicha handle or key 12 may be fitted for rotating it. The screw member 11extends through an aperture in the transverse member 8 of one of theL-shaped structures and through an internally screw-threaded block 13secured to the vertical member of the L-shaped structure; and a portionof the screw member 11 of opposite thread passes through a similarinternally threaded block secured to the vertical member of the otherL-shaped structure which forms the support for the other end of thescrew member, the further extension of the screw member simplyprojecting beyond this second block.

Thus when the handle is turned in one direction, the two L-shapedstructures are brought towards one another by equal amounts, and whenthe handle is turned in the other direction, the two Lshaped members aremoved away from each other by equal amounts.

Conveniently, two holes 14 are drilled at the top of each of thevertical members of the L-shaped structures to enable these members tobe lengthened should it be necessary.

Furthermore, two angle brackets 4 drilled through their vertical sidesmay be fixed one on each end of the top of the horizontal beam structureto enable other formwork to be secured by nails or screws when required;and a closing plate 3 is secured in the middle of the top of thehorizontal beam structure. I

Also three spaced spigots 15 may be secured as by welding to theunderside of the horizontal beam to locate adjustable steel props whensupporting the beam clamps. The middle spigot may be used when lightbeams are being cased, and the outer spigots may be used when usingformwork for larger beams.

Various other modifications may be made within the scope of theinvention. Thus the side beams can be of angle iron.

What is claimed is:

l. A clamp for holding together the formworkof casing used for castingconcrete beams in situ, comprising a beam structure having alongitudinally-extending channel formed therein which is closed at eachend by closure plates fitted to the ends of said beam structure, saidclosure plates each having an aperture through which passes a rotatablescrew-threaded member extending the length of said channel and arrangedto pass through correspondingly-threaded apertures in a pair of opposed,braced, L-shaped clamping members having flat underneath surfaces whichslide along the bottom of said channel, said screw-threaded memberhaving a right hand thread over one part of its length and a left handthread over another part of its length whereby rotation of said memberis effective to move said clamping members in opposite directionsthrough equal distances, said beam structure being provided on theunderside thereof with means for locating adjustable steel props, andangle brackets on the sides of said L-shaped members slidable on theupper outer surfaces of the beam structure.

2. A clamp for holding together the formwork of casing used for castingconcrete beams in situ, comprising a beam structure having alongitudinally-extending channel formed therein which is closed at eachend by closure plates fitted to the ends of said beam structure, saidclosure plates serving as bearing members for the ends of a rotatablerod having a right hand screw thread and a left hand screw thread overdifferent parts of its length, which rod extends longitudinally of saidchannel and passes through correspondingly-threaded apertures in a pairof opposed, braced, L-shaped clamping members having flat underneathsurfaces which slide along the bottom of said channel, and provided withangle brackets on their sides which slide on the upper outer surfaces ofsaid beam structure, said beam structure being provided on the undersideportion thereof with three spigots, one at each end and one in themiddle of said underside portion.

3. A clamp for holding together the formwork of cas ing used for castingconcrete beams in situ, comprising a beam structure having a1ongitudinally-extending channel formed therein which is closed at eachend by closure plates fitted to the ends of said beam structure, saidclosure plates each having an aperture therein, a rotatablescrewthreaded member extending the length of said channel and passingthrough said apertures in the closure plates, a pair of opposed, bracedL-shaped clamping members having flat underneath surfaces which slidealong the bottom of the channel, said L-shaped clamping members beingprovided with threaded apertures through which the rotatablescrew-threaded member passes, said screw-threaded member having a righthand thread over one part of its length and a left hand thread overanother part of its length whereby rotation of said member is effectiveto move the said clamping members in opposite directions through equaldistances, said beam structure being provided on the underside thereofwith means whereby said beam structure may be located on supportingmeans, and the upright portions of both of said L-shaped clampingmembers being apertured near their upper ends whereby extension membersmaybe secured to said upright portions.

References Cited in the'fileof this patent 4. Hinds..,.,. Nov. 9, 1 926Buttcrworth May 22, I928 Wilmesherr June 2, 1936 De Vigier Dec. 20, 1938Larson May 5, 1953 FOREIGN PATENTS France July 6, 1923

